We have been motoring through less than 5 knots of wind at 2000 RPM using one engine at a time and making 4.5 to 5 knots. With the calm conditions, at these low speeds, our new Yanmar diesels are remarkably fuel efficient, making between 5- 8 miles per gallon, about what my Ford Club Wagon does on city streets. Tonight, however, is the end of our motor sailing. We will be past the 130th meridian, where wind lives (we hope) and we have no more fuel to spend, we must hold 1/4 tank in both port and starbord fuel tanks for getting the rest of the way in. We will be a sailboat looking for wind to fill our sails and sailing where the wind will take us.
In describing our "gyre" study area, we have used the 130th meridian as our starting point. In travelling east toward it, we have seen the high levels of debris in the "garbage patch" diminish, but still it persists. We did a one hour manta trawl today, and it too looked like it had more plastic than plankton. The "macro" or large debris collection using dip nets off the bow started slowly, but picked up as the day went on.
Here is a partial list:
1430 27cm diameter green glass fishing float with line and barnacles
1430 Red 5 gal bucket with small fish swimming inside
1440 Styrofoam cylinder with bird droppings showing consumption of barnacles like those attached to float
1600 Red screw in light bulb 9'' long
We have been picking up numerous medium-sized fragments, pieces of line and plastic film withouth logging them in.
We are still seeing patches of plastic fragments as well as single ones passing by. Tomorrow we will do another manta trawl on the eastern side of the 130th meridian and see if it holds enough plastic for us to consider enlarging the area we consider holding significant debris concentrations.
One interesting question has to do with the fouling of plastic films. The photo shows a piece of plastic film, where algae appears to be growing more densely in the creases, giving the film a "crazed" appearance. In our original 1999 study, plastic films comprised about a fourth of all plastics by count. Perhaps the breakdown of the films is accelerated by algal fouling.
Another issue is the use of unsealed, unenclosed styrofoam in the aquatic environment. These floats are made by blowing gas into melted polystyrene beads, and then adhering the beads loosely together. As anyone knows who has worked with this material, the little beads easily detach when they are hit or rubbed and create little styrofoam "nurdles" that choke waterways and stormwater systems. The material is used for dock floats on Big Bear Lake, and I have observed a "bathtub ring" of them around the lake at the high water mark. Since the original polystyrene is heavier than water, and the foamed polystyrene floats, it is likely that at a certain point in its breakdown cycle, the foamed polystyrene will have the exact density of the water itself and will move to all compartments of the water column, along with all the pollutants it has absorbed, or were used in its manufacture.
We had not seen albatross for two days, but today we were visited by a Laysan along with our Glaucous-winged Gull, who also had been absent.
Aloha and gracias por sus atenciones desde ORV Alguita,